Primary cover shifter shaft seal.
Harley OE Part Num: 34035-52 Fits: 1952-1956 K Model & 1957-1985 Ironhead Sportster
Harley OE Part Num: 37101-84B Fits: 1986-2005 Evo Sportster
Harley OE Part Num: 37107-06 Fits: 2006-Present Rubber Mount Evo Sportster